Air pollution and bronchitic symptoms in Southern California children with asthma.

The association of air pollution with the prevalence of chronic lower respiratory tract symptoms among children with a history of asthma or related symptoms was examined in a cross-sectional study. Parents of a total of 3,676 fourth, seventh, and tenth graders from classrooms in 12 communities in Southern California completed questionnaires that characterized the children's histories of respiratory illness and associated risk factors. The prevalences of bronchitis, chronic phlegm, and chronic cough were investigated among children with a history of asthma, wheeze without diagnosed asthma, and neither wheeze nor asthma. Average ambient annual exposure to ozone, particulate matter (PM(10) and PM(2.5); [less than/equal to] 10 microm and < 2.5 microm in aerodynamic diameter, respectively), acid vapor, and nitrogen dioxide (NO(2)) was estimated from monitoring stations in each community. Positive associations between air pollution and bronchitis and phlegm were observed only among children with asthma. As PM(10) increased across communities, there was a corresponding increase in the risk per interquartile range of bronchitis [odds ratio (OR) 1.4/19 microg/m(3); 95% confidence interval (CI), 1.1-1.8). Increased prevalence of phlegm was significantly associated with increasing exposure to all ambient pollutants except ozone. The strongest association was for NO(2), based on relative risk per interquartile range in the 12 communities (OR 2.7/24 ppb; CI, 1.4-5.3). The results suggest that children with a prior diagnosis of asthma are more likely to develop persistent lower respiratory tract symptoms when exposed to air pollution in Southern California.     

The relationship between outdoor air quality and respiratory symptoms in young children

The aim of this study was to investigate the relationship between air pollution and respiratory symptoms in young children. A total of 263 children at high risk of developing asthma or atopy were recruited antenatally and all respiratory symptoms experienced by the children were recorded by their parents for five years. Daily pollutant concentrations and meteorological data (ambient temperature and humidity) were collected from network monitoring sites. Logistic regression models investigating relationships between individual air pollutants and respiratory symptoms showed significant associations between Ozone (O3) (1 h and 8 h) concentrations and raised body temperature (lag 0); Carbon monoxide (CO) (8 h) and wheeze/rattle and runny/blocked nose (lag 5 and additive exposure over 5 days); Nitrogen dioxide (NO2) (24 h) concentrations and cough (lag 0 and additive exposure over 5 days) and PM2.5 and visibility (BSP) (1 h) with cough (lag 0). These associations were observed even though air pollutant concentrations were below national standards throughout the study period.     

Dog ownership enhances symptomatic responses to air pollution in children with asthma

BACKGROUND: Experimental data suggest that asthma exacerbation by ambient air pollutants is enhanced by exposure to endotoxin and allergens; however, there is little supporting epidemiologic evidence. METHODS: We evaluated whether the association of exposure to air pollution with annual prevalence of chronic cough, phlegm production, or bronchitis was modified by dog and cat ownership (indicators of allergen and endotoxin exposure). The study population consisted of 475 Southern California children with asthma from a longitudinal cohort of participants in the Children's Health Study. We estimated average annual ambient exposure to nitrogen dioxide, ozone, particulate matter < 10, 2.5, and 10-2.5 microm in aerodynamic diameter (PM10, PM2.5, and PM10-2.5, respectively), elemental and organic carbon, and acid vapor from monitoring stations in each of the 12 study communities. Multivariate models were used to examine the effect of yearly variation of each pollutant. Effects were scaled to the variability that is common for each pollutant in representative communities in Southern California. RESULTS: Among children owning a dog, there were strong associations between bronchitic symptoms and all pollutants examined. Odds ratios ranged from 1.30 per 4.2 microg/m3 for PM10-2.5 [95% confidence interval (CI), 0.91-1.87) to 1.91 per 1.2 microg/m3 for organic carbon (95% CI, 1.34-2.71). Effects were somewhat larger among children who owned both a cat and dog. There were no effects or small effects with wide CIs among children without a dog and among children who owned only a cat. CONCLUSION: Our results suggest that dog ownership, a source of residential exposure to endotoxin, may worsen the relationship between air pollution and respiratory symptoms in asthmatic children.     

Acute effects of low levels of ambient ozone on peak expiratory flow rate in a cohort of Australian children

BACKGROUND: We enrolled a cohort of primary schoolchildren with a history of wheeze (n = 148) in an 11-month longitudinal study to examine the relationship between ambient ozone concentrations and peak expiratory flow rate. METHODS: Enrolled children recorded peak expiratory flow rates (PEFR) twice daily. We obtained air pollution, meteorological and pollen data. In all, 125 children remained in the final analysis. RESULTS: We found a significant negative association between daily mean deviation in PEFR and same-day mean daytime ozone concentration (beta-coefficient = 0.88; P = 0.04) after adjusting for co-pollutants, time trend, meteorological variables, pollen count and ALTERNARIA: count. The association was stronger in a subgroup of children with bronchial hyperreactivity and a doctor diagnosis of asthma (beta-coefficient = -2.61; P = 0.001). There was no significant association between PEFR and same-day daily daytime maximum ozone concentration. We also demonstrated a dose-response relationship with mean daytime ozone concentration. CONCLUSIONS: Moderate levels of ambient ozone have an adverse health effect on children with a history of wheezing, and this effect is larger in children with bronchial hyperreactivity and a doctor diagnosis of asthma.     

Air pollution and childhood asthma emergency hospital admissions: estimating intra-city regional variations

In recent years childhood asthma has increased. Although the precipitants of childhood asthma are yet to be established possible contributing factors are local ambient air pollutants. This study aims to assess associations of regional ambient air pollutants on emergency department childhood asthma presentations across four regions of the city of Melbourne, Australia. Daily emergency department (ED) presentations for asthma in children were studied for the years 2000 and 2001. Estimates of local air pollutant levels were obtained using simulation modelling techniques. Generalized Additive Models were used to examine associations between combined local levels of air pollutants and childhood asthma ED presentations adjusting for seasonal variation, day of week effects, and meteorological variables. There was consistent associations between childhood ED asthma presentations and regional concentration of PM10, with a strongest association of RR = 1.17 (95% CI 1.05 to 1.31) in the central district of Melbourne. NO2 and Ozone was associated with increased childhood asthma ED presentations in the Western districts. This study suggests that regional concentrations of PM10 may have a significant effect on childhood asthma morbidity. In addition, ozone may play a role however, its effect may vary by geographical region.     

臭氧暴露与儿童哮喘就诊人数相关性的Meta分析

目的 系统性评价臭氧暴露对儿童哮喘就诊人数的影响。方法 计算机检索中国知网、万方数据库、维普中文期刊数据库、Pubmed、Embase、Cochrane 等数据库,以哮喘、臭氧、空气污染物、asthma、bronchial asthma、wheeze、respiratory tract allergy、ozone、O3、gaseous pollutants为检索词,检索从建库至2020年8月26日公开发表的文献,依据纳入标准和排除标准进行文献筛选。最终纳入文献使用Revman 5.4进行meta分析。结果 最终纳入文献14篇,meta分析结果显示,环境臭氧每上升10 μg/m3,哮喘儿童就诊人数平均增加1.33%。亚组分析结果显示哮喘儿童因臭氧暴露入院人数与急诊就诊人数基本一致,但急诊就诊受臭氧浓度影响更大。根据研究类型分析显示两种研究方法均支持儿童哮喘就诊人数与臭氧浓度呈正相关。结论 环境臭氧浓度上升可导致儿童哮喘就诊人数增加,且因臭氧暴露导致的急诊就诊人数高于入院就诊人数,降低环境臭氧浓度可有效减轻哮喘疾病负担。     

Elevated ambient air zinc increases pediatric asthma morbidity

BACKGROUND: Recent studies indicate that the composition of fine particulate matter [PM 相似文献   

深圳市大气PM10与呼吸系统疾病日门诊量的时间序列分析

目的探讨大气可吸入颗粒污染物（PM10）对医院呼吸系统疾病门诊量的影响。方法2012年1月1日至12月31日疾病资料来源于深圳市2家三级甲等综合性医院逐日门诊病例资料,空气污染物资料来自深圳市环境监测站,气象资料来自气象局。采用广义相加Poisson回归模型的时间序列分析,在控制长期趋势、星期几效应和气象等影响因素后,对大气PM10日均浓度与呼吸系统疾病日门诊量的关系和滞后效应进行分析。结果深圳市2012年全年日均大气PM10浓度为0．052mg／m^3,符合国家二级标准,2家医院全年呼吸系统门诊量为562174人次,平均1535．99人次／d。广义相加模型分析结果发现PM10日均浓度与呼吸系统疾病门诊量存在正相关关系。滞后6d时PM10日均浓度对呼吸系统疾病门诊量的影响最强[相对危险度（RR）为1．0047,95％CI：1．0036—1．0058]。引入CO、O3、NO2、SO2进行多污染物模型分析发现,多污染物模型的RR值相对单污染物模型有升有降（均P〈0．05）,其中以双污染物模型PM10＋SO2和三污染物模型PM10＋CO＋SO2中的PM10的RR值最高,分别为1．0059、1．0067。结论深圳市大气PM10污染与医院呼吸系统疾病日门诊量呈正相关关系,且存在滞后效应。     

Air pollution and ED visits for asthma in Australian children: a case-crossover analysis

OBJECTIVE: We aimed to determine the effects of ambient air pollutants on emergency department (ED) visits for asthma in children. METHODS: We obtained routinely collected ED visit data for asthma (ICD9 493) and air pollution (PM(10), PM(2.5), O(3), NO(2), CO and SO(2)) and meteorological data for metropolitan Sydney for 1997-2001. We used the time stratified case-crossover design and conditional logistic regression to model the association between air pollutants and ED visits for four age-groups (1-4, 5-9, 10-14 and 1-14 years). Estimated relative risks for asthma ED visits were calculated for an exposure corresponding to the inter-quartile range in pollutant level. We included same day average temperature, same day relative humidity, daily temperature range, school holidays and public holidays in all models. RESULTS: Associations between ambient air pollutants and ED visits for asthma in children were most consistent for all six air pollutants in the 1-4 years age-group, for particulates and CO in the 5-9 years age-group and for CO in the 10-14 years age-group. The greatest effects were most consistently observed for lag 0 and effects were greater in the warm months for particulates, O(3) and NO(2). In two pollutant models, effect sizes were generally smaller compared to those derived from single pollutant models. CONCLUSION: We observed the effects of ambient air pollutants on ED attendances for asthma in a city where the ambient concentrations of air pollutants are relatively low.     

Factor analysis of household factors: are they associated with respiratory conditions in Chinese children?

BACKGROUND: We explored methods to develop uncorrelated variables for epidemiological analysis models. They were used to examine associations between respiratory health outcomes and multiple household risk factors. METHODS: We analysed data collected in the Four Chinese Cities Study (FCCS) to examine health effects on prevalence rates of respiratory symptoms and illnesses in 7058 school children living in the four Chinese cities: Lanzhou, Chongqing, Wuhan, and Guangzhou. We used factor analysis approaches to reduce the number of the children's lifestyle/household variables and to develop new uncorrelated 'factor' variables. We used unconditional logistic regression models to examine associations between the factor variables and the respiratory health outcomes, while controlling for other covariates. RESULTS: Five factor variables were derived from 21 original variables: heating coal smoke, cooking coal smoke, socioeconomic status, ventilation, and environmental tobacco smoke (ETS) and parental asthma. We found that higher exposure to heating coal smoke was associated with higher reporting of cough with phlegm, wheeze, and asthma. Cooking coal smoke was not associated with any of the outcomes. Lower socioeconomic status was associated with lower reporting of persistent cough and bronchitis. Higher household ventilation was associated with lower reporting of persistent cough, persistent phlegm, cough with phlegm, bronchitis, and wheeze. Higher exposure to ETS and the presence of parental asthma were associated with higher reporting of persistent cough, persistent phlegm, cough with phlegm, bronchitis, wheeze, and asthma. CONCLUSIONS: Our study suggests that independent respiratory effects of exposure to indoor air pollution, heating coal smoke, and ETS may exist for the studied children.     

Traffic density and stationary sources of air pollution associated with wheeze, asthma, and immunoglobulin E from birth to age 5 years among New York City children

Exposures to ambient air traffic-related pollutants and their sources have been associated with respiratory and asthma morbidity in children. However, longitudinal investigation of the effects of traffic-related exposures during early childhood is limited. We examined associations of residential proximity and density of traffic and stationary sources of air pollution with wheeze, asthma, and immunoglobulin (Ig) E among New York City children between birth and age 5 years.Subjects included 593 Dominican and African American participants from the Columbia Center for Children's Environmental Health cohort. Prenatally, through age 5 years, residential and respiratory health data were collected every 3–6 months. At ages 2, 3, and 5 years, serum IgE was measured. Spatial data on the proximity and density of roadways and built environment were collected for a 250 m buffer around subjects' homes. Associations of wheeze, asthma, total IgE, and allergen-specific IgE with prenatal, earlier childhood, and concurrent exposures to air pollution sources were analyzed using generalized estimating equations or logistic regression.In repeated measures analyses, concurrent residential density of four-way intersections was associated significantly with wheeze (odds ratio: 1.26; 95% confidence interval [CI]: 1.01, 1.57). Age 1 exposures also were associated with wheeze at subsequent ages. Concurrent proximity to highway was associated more strongly with total IgE (ratio of the geometric mean levels: 1.25; 95% CI: 1.09, 1.42) than were prenatal or earlier childhood exposures. Positive associations also were observed between percent commercial building area and asthma, wheeze, and IgE and between proximity to stationary sources of air pollution and asthma.Longitudinal investigation suggests that among Dominican and African American children living in Northern Manhattan and South Bronx during ages 0–5 years, residence in neighborhoods with high density of traffic and industrial facilities may contribute to chronic respiratory morbidity, and concurrent, prenatal, and earlier childhood exposures may be important. These findings may have broad implications for other urban populations that commonly have high asthma prevalence and exposure to a high density of traffic and stationary air pollution sources.     

Association of ambient air pollution with respiratory hospitalization in a government-designated "area of concern": the case of Windsor, Ontario

This study is part of a larger research program to examine the relationship between ambient air quality and health in Windsor, Ontario, Canada. We assessed the association between air pollution and daily respiratory hospitalization for different age and sex groups from 1995 to 2000. The pollutants included were nitrogen dioxide, sulfur dioxide, carbon monoxide, ozone, particulate matter 10 microm in diameter (PM10), coefficient of haze (COH), and total reduced sulfur (TRS). We calculated relative risk (RR) estimates using both time-series and case-crossover methods after controlling for appropriate confounders (temperature, humidity, and change in barometric pressure). The results of both analyses were consistent. We found associations between NO2, SO2, CO, COH, or PM10 and daily hospital admission of respiratory diseases especially among females. For females 0-14 years of age, there was 1-day delayed effect of NO2 (RR = 1.19, case-crossover method), a current-day SO2 (RR = 1.11, time series), and current-day and 1- and 2-day delayed effects for CO by case crossover (RR = 1.15, 1.19, 1.22, respectively). Time-series analysis showed that 1-day delayed effect of PM10 on respiratory admissions of adult males (15-64 years of age), with an RR of 1.18. COH had significant effects on female respiratory hospitalization, especially for 2-day delayed effects on adult females, with RRs of 1.15 and 1.29 using time-series and case-crossover analysis, respectively. There were no significant associations between O3 and TRS with respiratory admissions. These findings provide policy makers with current risks estimates of respiratory hospitalization as a result of poor ambient air quality in a government designated "area of concern."     

An association between fine particles and asthma emergency department visits for children in Seattle.

Asthma is the most common chronic illness of childhood and its prevalence is increasing, causing much concern for identification of risk factors such as air pollution. We previously conducted a study showing a relationship between asthma visits in all persons < 65 years of age to emergency departments (EDs) and air pollution in Seattle, Washington. In that study the most frequent zip codes of the visits were in the inner city. The Seattle-King County Department of Public Health (Seattle, WA) subsequently published a report which showed that the hospitalization rate for children in the inner city was over 600/100,000, whereas it was < 100/100,000 for children living in the suburbs. Therefore, we conducted the present study to evaluate whether asthma visits to hospital emergency departments in the inner city of Seattle were associated with outdoor air pollution levels. ED visits to six hospitals for asthma and daily air pollution data were obtained for 15 months during 1995 and 1996. The association between air pollution and childhood ED visits for asthma from the inner city area with high asthma hospitalization rates were compared with those from lower hospital utilization areas. Daily ED counts were regressed against fine particulate matter (PM), carbon monoxide (CO), sulfur dioxide, and nitrogen dioxide using a semiparametric Poisson regression model. Significant associations were found between ED visits for asthma in children and fine PM and CO. A change of 11 microg/m3 in fine PM was associated with a relative rate of 1.15 [95% confidence interval (CI), 1.08-1.23]. There was no stronger association between ED visits for asthma and air pollution in the higher hospital utilization area than in the lower utilization area. These findings were seen when estimated PM2.5 concentrations were below the newly adopted annual National Ambient Air Quality Standard of 15 microg/m3.     

Air pollution and emergency room visits for asthma in Santa Clara County, California.

During the winters of 1986-1987 through 1991-1992, rainfall throughout much of Northern California was subnormal, resulting in intermittent accumulation of air pollution, much of which was attributable to residential wood combustion (RWC). This investigation examined whether there was a relationship between ambient air pollution in Santa Clara County, California and emergency room visits for asthma during the winters of 1988-1989 through 1991-1992. Emergency room (ER) records from three acute-care hospitals were abstracted to compile daily visits for asthma and a control diagnosis (gastroenteritis) for 3-month periods during each winter. Air monitoring data included daily coefficient of haze (COH) and every-other-day particulate matter with aerodynamic diameter equal to or less than 10 microns (PM10, 24-hr average), as well as hourly nitrogen dioxide and ozone concentrations. Daily COH measurements were used to predict values for missing days of PM10 to develop a complete PM10 time series. Daily data were also obtained for temperature, precipitation, and relative humidity. In time-series analyses using Poisson regression, consistent relationships were found between ER visits for asthma and PM10. Same-day nitrogen dioxide concentrations were also associated with asthma ER visits, while ozone was not. Because there was a significant interaction between PM10 and minimum temperature in this data set, estimates of relative risks (RRs) for PM10-associated asthma ER visits were temperature-dependent. A 60 micrograms/m3 change in PM10 (2-day lag) corresponded to RRs of 1.43 (95% CI = 1.18-1.69) at 20 degrees F, representing the low end of the temperature distribution, 1.27 (95% CI = 1.13-1.42) at 30 degrees F, and 1.11 (95% CI = 1.03-1.19) at 41 degrees F, the mean of the observed minimum temperature. ER visits for gastroenteritis were not significantly associated with any pollutant variable. Several sensitivity analyses, including the use of robust regressions and of nonparametric methods for fitting time trends and temperature effects in the data, supported these findings. These results demonstrate an association between ambient wintertime PM10 and exacerbations of asthma in an area where one of the principal sources of PM10 is RWC.     

Asthma exacerbation is associated with particulate matter source factors in children in New York City

Exposure to fine particulate matter (PM_2.5) is linked with asthma exacerbation; however, the role played by specific PM sources is not well understood. Our objective was to investigate the associations between daily cough and wheeze symptoms in a panel of asthmatic children and PM source factors determined by receptor modeling using positive matrix factorization (PMF). We studied 36 children with moderate-to-severe asthma in New York City over both a warm and a cold season. Exposure to ambient air pollutants, including PM_2.5 elements and elemental and organic carbon fractions, was characterized. The mean ambient PM_2.5 concentration for the study periods was 12.0?±?6.7 μg/m³. Six factors were resolved using PMF, including oil, road dust, ships, regional, salt, and traffic. When adjusted for ozone, cough and wheeze symptoms were most strongly associated with the regional and salt factors. Results using tracer elements (as determined from PMF analyses) showed some inconsistency, with two tracers for road dust (K and Si) showing associations in opposite directions to each other. Positive associations were also observed for S, which is a tracer of regional PM. Significant negative associations were observed for the oil factor and one of its tracers (Zn). Mostly nonsignificant associations were found for carbon fractions, with the exception of pyrolized carbon and two elemental carbon fractions. Our results indicate that asthma symptoms are associated with regional and salt factors. In this study, the regional factor was comprised of sulfate as well as carbon-containing PM, the latter which is likely derived from both anthropogenic and biogenic sources.     

Air pollution and exacerbation of asthma in African-American children in Los Angeles

Significant increases in asthma morbidity and mortality in the United States have occurred since the 1970s, particularly among African-Americans. Exposure to various environmental factors, including air pollutants and allergens, has been suggested as a partial explanation of these trends. To examine relations between several air pollutants and asthma exacerbation in African-Americans, we recruited a panel of 138 children in central Los Angeles. We recorded daily data on respiratory symptoms and medication use for 13 weeks and examined these data in conjunction with data on ozone (O3) nitrogen dioxide (NO2), particulate matter (PM10 and PM2.5), meteorological variables, pollens, and molds. Using generalized estimating equations, we found associations between respiratory symptom occurrence and several environmental factors. For example, new episodes of cough were associated with exposure to PM10 (OR = 1.25; 95% CI = 1.12-1.39; interquartile range [IQR] = 17 microg/m3, 24-hour average), PM2.5 (OR = 1.10; 95% CI = 1.03-1.18; IQR = 30 microg/m3, 12-hour average), NO2, and the molds Cladosporium and Alternaria, but not with exposure to O3 or pollen. The factors PM10 and O3 were associated with the use of extra asthma medication. For this population several bioaerosols and air pollutants had effects that may be clinically significant.     

Association between hospital emergency visits for asthma and air pollution in Valencia,Spain

OBJECTIVE: To assess the short term effect of concentrations of black smoke, sulphur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3) in ambient air on emergency room visits for asthma in the city of Valencia, Spain during the period 1994-5. METHODS: Ecological study with time series data and application of Poisson regression. Associations between number of daily emergency visits in a city''s hospital and concentrations of air pollutants were analysed taking into account potential confounding factors by the standardised protocol of the air pollution and health: a European approach (APHEA) project. RESULTS: Mean (range) daily number of emergency room visits for asthma was 1 (0-5). Concentrations of all pollutants studied remained within current air quality standards. The association between an increase of 10 micrograms/m3 in ambient air pollution and asthma, measured as a relative risk (RR) of emergency visits, was significant for NO2 24 hour mean (lag 0, RR 1.076, 95% confidence interval (95% CI) 1.020 to 1.134), NO2 hour maximum (lag 0, RR 1.037, 95% CI 1.008 to 1.066), and O3 hour maximum (lag 1, RR 1.063, CI 95% 1.014 to 1.114). The association was not significant for SO2 or for black smoke during the period analysed. The effects were not significantly different for the time of year, cold months (November to April), or warm months (May to October). CONCLUSIONS: Current concentrations of ambient air pollution in Valencia are significantly associated with emergency room visits for asthma. This association is high and more consistent for NO2 and O3 than for particulate matter and SO2 (classic pollutants).       

Ambient air pollution and respiratory emergency department visits

BACKGROUND: A number of emergency department studies have corroborated findings from mortality and hospital admission studies regarding an association of ambient air pollution and respiratory outcomes. More refined assessment has been limited by study size and available air quality data. METHODS: Measurements of 5 pollutants (particulate matter [PM10], ozone, nitrogen dioxide [NO2], carbon monoxide [CO], and sulfur dioxide [SO2]) were available for the entire study period (1 January 1993 to 31 August 2000); detailed measurements of particulate matter were available for 25 months. We obtained data on 4 million emergency department visits from 31 hospitals in Atlanta. Visits for asthma, chronic obstructive pulmonary disease, upper respiratory infection, and pneumonia were assessed in relation to air pollutants using Poisson generalized estimating equations. RESULTS: In single-pollutant models examining 3-day moving averages of pollutants (lags 0, 1, and 2): standard deviation increases of ozone, NO2, CO, and PM10 were associated with 1-3% increases in URI visits; a 2 microg/m increase of PM2.5 organic carbon was associated with a 3% increase in pneumonia visits; and standard deviation increases of NO2 and CO were associated with 2-3% increases in chronic obstructive pulmonary disease visits. Positive associations persisted beyond 3 days for several of the outcomes, and over a week for asthma. CONCLUSIONS: The results of this study contribute to the evidence of an association of several correlated gaseous and particulate pollutants, including ozone, NO2, CO, PM, and organic carbon, with specific respiratory conditions.     

Air pollution,socioeconomic position,and emergency hospital visits for asthma in Seoul,Korea

Objective Some epidemiological literature has observed that air pollution effects on health differed across regional or individual socioeconomic position. This study evaluated whether regional and individual socioeconomic position, as indicated by health insurance premiums, modified the effect of air pollution on hospital visits for asthma. Methods Effects of ambient air pollutants (particulate matter, carbon monoxide, sulfur dioxide, nitrogen dioxide, and ozone) on 92,535 emergency out-patient hospital visits for asthma in Seoul, Korea during 2002 were estimated using case-crossover analysis, adjusting for time trend, weather conditions, and seasonality. Next, interactions between air pollutants and Korean National Health Insurance premium (1) for the individual patient and (2) averaged across the patient’s residence district, were entered, first singly then jointly, in the models. Results Relative risks of emergency outpatient hospital visits were all positively and significantly associated with interquartile increases for selected lags for all air pollutants. In the regression model with interaction terms for both individual premium and regional-average premium, associations with all five-air pollutants ranged from 1.03 to 1.09 times higher among the lowest premium districts compared to the highest premium districts. Of all the pollutants, nitrogen dioxide showed the strongest associations in lower premium districts compared to the higher premium districts. Individual socioeconomic position did not modify the associations in either the single or joint interaction models. Conclusion In Seoul, community but not individual socioeconomic conditions modified risk of asthma hospital visits on high air pollution days.     

Social disadvantage, air pollution, and asthma physician visits in Toronto, Canada

Background

Previous research demonstrates that ambient air pollution exacerbates asthma. Asthma morbidity also varies with socioeconomic position (SEP). Few studies have examined if ambient air pollution has a differential impact on income subgroups of the population. This paper investigates socioeconomic variation in ambulatory physician consultations for asthma and assesses possible effect modification of SEP on the association between physician visits and air pollution for children aged 1-17 and adults aged 18-64 in Toronto, Canada, between 1992 and 2001.

Methods

Generalized additive models and generalized linear models were used to estimate the adjusted risk of asthma physician visits associated with an interquartile range increase in sulfur dioxide (SO₂), nitrogen dioxide (NO₂), particulate matter (PM_2.5), and ozone (O₃).

Results

A socioeconomic gradient in the number of physician visits was observed among children and adults and both sexes. SO₂, NO₂, and PM_2.5 had positive associations with physician visits. The risk ratios for the low socioeconomic group were significantly greater than those for the high socioeconomic group in several of the models of SO₂ and PM_2.5.

Conclusions

These findings suggest increased ambulatory physician visits represent another component of the public health impact of urban air pollution. The burden of this impact may be borne disproportionately by those with lower SEP. Clarifying the role of SEP in altering susceptibility to the effects of air pollution is essential not only to inform revisions of ambient air quality standards, but also to design public health interventions to reduce health impacts on sensitive subgroups of the population.